An implantable optical sensor (1) comprising a substrate (2) and at least one optical microstructure (3) for evanescent field sensing integrated with the substrate (2), the at least one optical microstructure (3) being positioned to form an optical interaction area (4) on a part of a surface (5) of the substrate (2), the optical assembly (1) further comprising a thin protective layer (6) covering at least the optical interaction area (4), the thin protective layer (6) being in a predetermined material with corrosion-protection characteristics and having a predetermined thickness, so as not to affect the evanescent field sensing.

An overheat detection system for an aircraft, the system comprising a first bleed monitoring computer, BMC1, configured to identify leakages in a pneumatic system, the BMC1 including a first optical controller, a second bleed monitoring computer, BMC2, the BMC2 including a second optical controller, an optical fiber link connecting the first optical controller of the BMC1 and the second optical controller of the BMC2 for communication between the BMC1 and the BCM2 and between the first optical controller and the second optical controller, wherein the first and the second optical controllers are configured to detect overheat of the optical fiber link based on a wavelength shift of a modulated optical signal transmitted through the optical fiber link, and transmit signals to the first BMC1 and the second BMC2 based at least on the detected overheat.

A sensor system includes a sensor network comprising at least one optical fiber having one or more optical sensors. At least one of the optical sensors is arranged to sense vibration of an electrical device and to produce a time variation in light output in response to the vibration. A detector generates an electrical time domain signal in response to the time variation in light output. An analyzer acquires a snapshot frequency component signal which comprises one or more time varying signals of frequency components of the time domain signal over a data acquisition time period. The analyzer detects a condition of the electrical device based on the snapshot frequency component signal.

A subsurface impact protection system for protecting an underground asset is provided. The protection system includes a subsurface polymer layer provided above the asset to prevent impact forces from reaching the asset. A sensor network is embedded in the polymer layer. The sensor network comprises optical fibers each including one or more fiber optic sensors. The optical fibers receive an input signal from a source and transmit it through the fiber. At the output end of the fiber is an optical detector that measures light properties of the output optical signal indicative of environmental conditions near the polymer layer. The sensor network transmits a signal including measured light or environmental parameters to a monitoring computing system. In some embodiments, the polymer layer includes a protective mesh made up of a plurality of high density polyethylene strands in a woven pattern. A method of protecting an underground asset is also provided.

Direct detection of carbon dioxide leakage in a carbon storage well is obtained using an optical fiber adapted to be positioned in the carbon storage well, a detection unit operatively connected to the optical fiber, and a leak sensor section incorporated in the optical fiber.

Distributed fiber optic sensors formed by covering the fibers with tubing are provided. The tubing including responsive materials formulated or configured to, responsive to exposure to one of a target chemical species and a target radiation particle, change a relative size and generate a localized effect on or in the optical fiber.

A method for testing an optical assembly (1) which has an optical microstructure (3) integrated with a substrate (2). The optical microstructure (3) is positioned to form an external optical interaction area (4) on a part of a surface (5) of the substrate (2). A cover cap (6) seals at least a part of the surface (5) of the substrate (2) adjacent to the optical microstructure (3) to obtain a sealed cavity (9). An optical feedthrough (10) is integrated in the substrate (2) to form an external communication path from within the sealed cavity (9). The optical feedthrough (10) allows communication of a physical parameter value which is measured inside the sealed cavity (9) to outside the sealed cavity (9). The physical parameter value is associated with a measure of hermeticity of the sealed cavity (9).

Pipeline segments can contain cables, such as communication cables (e.g., fiber optic cables) within insulation material surrounding the pipeline segments. Cables can be embedded within the insulation material, run through conduits embedded within the insulation material, placed in channels formed in the insulation material, or otherwise. Channels containing one or more cables can be filled with supplemental insulation material, thus securing the cables within the channels. Pipelines created as disclosed herein can enable data transfer between distant points without the need to lay fiber optic cable in addition to the pipeline. Further, fiber optic cable embedded thusly can be used to sense conditions in the pipeline, such as leaks, seismic activity, strain, and temperature information.

A leak indicator includes a substrate comprising a permeable material with an immobilized reactant embedded in the substrate at a fixed location and a mobile reactant disposed at an initial location on the substrate. The initial location of the mobile reactant is spaced apart from the fixed location of the immobilized reactant. The mobile reactant is transported through the substrate by water to the fixed location of the immobilized reactant. The mobile reactant and the immobilized reactant interact to indicate a leak when the mobile reactant reaches the immobilized reactant.

A leak through the thickness of a structure is detected from one side of the structure using a leak detection layer. The leak detection layer exhibits visually observable changes when exposed to an air leak.